A new study indicates that dust from regions boarding deserts has a different composition than previously thought. This in turn can alter the impact of dust on climate change, for example via changing the net heating/cooling effect of dust and its effect glacial melting. (Source: bachmont, Creative Commons)

The study finds that there's more large dust particles in the atmosphere than previously thought. This may mean that climate change models will need to be rerun and reanalyzed to take into account the complex effects of atmospheric dust. (Source: UCAR)

More large dust particles are present than previously, thought, may act both to cool or accelerate melting

Some
of the Earth's tiniest naturally occurring particles may play a much different role in global climate change than previously thought. New findings reveal
that models scientists
have long used to estimate the causes and effects of global warming
may be flawed due to errors in one of their significant inputs -- atmospheric dust.

This revelation is an indirect conclusion of a new
study published in
the journal Proceedings
of the National Academy of Sciences by
Jasper Kok, a climatology researcher with The National Center for
Atmospheric Research (NCAR).

I. Ice Melt, Cooling, and Large Dust Particles

The
study's key conclusion was to show that the ratio of small soil dust
particles (clay), which cool the atmosphere, to large soil dust
particles (silt), which may heat or cool depending on their size, may be much lower than previous estimated using empirical (observation based models). While the number of small dust particles, according to our discussion with Professor Kok, is approximately the same as previously thought, the number of large particles are much higher.

This is a critical finding
because it means that current global circulation models (GCMs) used in broader climate change models, may significantly overestimate the net cooling effect per volume of dust (given the greater occurrence of large silt, which favors heating). The overestimation of the cooling is reported especially high at the top of the atmosphere (TOA), where it may be overestimated by as much as a factor of 15.

It is also critical as these large silt particles tend to precipitate and can play an important role of accelerating glacial melting. Thus atmospheric dust may not only warm the earth more than previously estimated, but may also lead directly to one of the observed effects often associated with climate change -- glacial melting.

II. A Dusty Surprise

To better understand the study, it's important to get a picture of what these particles are.

Mineral
dust originates when sand particles are blown by
the wind into soil, shattering it into microparticles. Major
sources of mineral dust include the southwestern United States,
northern Africa, Northeast Asia (the Gobi Desert) and Australia.

The sand essentially acts like tiny bullets, hammering dirt particles, which tend to be 20 microns or smaller and are thus known as PM20 sediment. This process, known as saltation ejects a mixed distribution of dust microparticles into the atmosphere, as the cracked particles' aerodynamic forces overwhelm their cohesive forces.

The
smallest resulting microparticles measure less than 2 microns (2000 nm).
These particles are known as clay. Past studies have shown that they tend to stay in the
atmosphere for long periods of time, reflecting light and cooling the
Earth.

Large microparticles, known as silt, can
reach 50 microns (50,000 nm) -- about the width of a human hair).
Their weight causes them to quickly fall out of the atmosphere. Depending on their size they can either exert a net cooling effect or a net heating effect. Silt larger than 5 microns in diameter tends to warm the earth (as reflection of outgoing radiation back towards the Earth overcomes sun-blocking effects), while silt between 2 and 5 microns tends to cool (as the sun blocking effects are more effective than the reflective effects). In that regard small silt acts much like clay, albeit being less effective at cooling.

Despite their quick precipitation all types of silt have another significant direct effect on the climate. After falling through the atmosphere, they tend to accumulate in mountain polar ice, concentrating
sunlight, absorbing heat and accelerating melting.

In order to
find the true ratio of the particles types, Professor Kok cleverly
combined mathematical theory and statistical data. To determine
the breaking method, he used brittle object breaking formulas
developed by mathematicians. Brittle objects, like glass, rocks
-- or soil -- break into a predictable distribution of small, medium,
and large particles.

Using these formulas, the
researcher turned to statistical information on arid soil, published
in a 1983 study Guillaume d'Almeida and Lothar Schüth from the
Institute for Meteorology at the University of Mainz in Germany.
By combining the two, he was able to arrive at what is thought to be
the most accurate statistical distribution for particle sizes
resulting from soil breaking published to date.

And the
results yielded a major surprise. They showed that the ratio of larger
particles to small particles (responsible for heating) was two to eight times higher than originally thought. In other words, this additional large dust may be both exerting more of a net warming effect on the atmosphere and more of a melting effect on glacial ice.

The difference in ratio is large enough that previous models may have even missed the sign of the net forcing from dust (there may have been a net warming due to global dust, rather than a net cooling). At the least, the dust's per unit cooling effect is much smaller than previously though.

This raises puzzling questions about historic cooling, which traditionally is accompanied by an increase in global dust. According to Professor Kok, "We know from paleo-records, such as ice cores and lake/ocean sediment cores, that the atmospheric dust concentration during, for example, ice ages, was several times higher than it is now."

The author believes that this is because current GCMs and climate change models significantly underestimate the current volumes of atmospheric dust circulation, and thus come close to the correct net forcing, despite overstating the dust's per-unit net cooling effect. If true, this could have important ramifications in the biology field, as the Earth's nutrient circulation model would change.

Another possibility not fully analyzed in the paper is that the cooling effect could instead be lesser, but the warming effect from other inputs e.g. carbon aerosols could be less than previously thought. This would be very significant if true, as it could have a bearing concerning to what degree current emissions need to be regulated.

A crucial question not discussed by the author, but that also seems apparent, is whether warming can trigger an increase in dust, which in turn reins in the system and results in a cooling. That is a critical question to assessing the possible impact of aerosol emissions, as it could indicate that the planet as the ability to counteract aerosol emissions, via an increase in dust, at least to an extent.

Again, Professor Kok emphasizes that how atmospheric dust levels change over time is still poorly understood. But based on our discussion with him, we received the impression that this is absolutely critical to determining how our climate will change in response to a variety of factors, including carbon dioxide emissions.

III.
Back to the Drawing Board

The
new findings by no means devalue the idea of using computer modeling
to study the Earth's climate. But they are an important
reminder that climate models are only as good as their inputs, and in
many cases those inputs are based on information that's
lacking.

It would be rash not to reevaluate at least some of the modeling work done to date, taking into account this new perspective on atmospheric dust.

How much or how little impact this study has on modeling will rest largely on determining more accurately how atmospheric dust levels vary with time. According to a brief conversation we had with Professor Kok, the levels of atmospheric dust and how they change with time is a poorly "understood" topic. Thus the study could potentially invalidate currently collected data from current warming models, or leave it largely unscathed. But it does indicate that a new round of data collection and verification is necessary to determine which is the case.

Despite the controversy that peripheral effect of the study will bring in the non-scientific community, which is preoccuppied with the kind of instant, absolute answers that can justify billion dollar policy decisions, most objective members of the climate change community will likely take the need for correction in stride.

The author states:

Climate scientists are acutely aware of the many uncertainties in climate models. They are an imperfect tool to estimate future climate, but they are probably the best tool we have. However, despite the many uncertainties, climate scientists are still able to say that, over long time periods (decades) over which greenhouse warming will overwhelm natural climate variability, the Earth will very likely warm. Exactly how much this warming will be, and how this varies regionally, is still uncertain... For this reason, much of the research in the climate sciences is directed towards reducing uncertainties in climate models by both better understanding processes that are already in the models (such as what my study has done), and by adding additional processes that had not yet been accounted for (the glacier melting by dust deposition has for example been added to some climate models in the last few years). My study is thus a small part of this much bigger effort.

And moreover, Professor Kok thinks that its important not to forget the results' beauty from a
mathematical perspective, in the rush to apply them to improving modeling. He states in the previous NSF press release,
"As small as [the particles] are, conglomerates of dust
particles in soils behave the same way on impact as a glass dropped
on a kitchen floor. Knowing this pattern can help us put
together a clearer picture of what our future climate will look
like. The idea that all these objects shatter in the same way
is a beautiful thing, actually. It's nature's way of creating
order in chaos."

Beautiful indeed. Professor Kok's
ability to focus on truly objective mathematical and scientific
analysis with regard to what is an increasing politicized topic is
exemplary as well. Given recent revelations [1][2][3],
this kind of objective dedication to scientific truth is not always
present in this field, so it's as refreshing to see that as it is
fascinating to observe the symmetry that underlies many laws of our
universe.

Update: Dec 31, 2010 11:10 a.m.-

We had a lengthy discussion with Professor Kok to clarify a couple of conclusions that the NSF press release seemed to be pointing at. Most importantly, Professor Kok explained to us that the levels of small dust was not less than previously expected, rather they were the same and the levels of large dust were higher.

He also explained that solar variance (generally within the range of +/- 0.1 percent of total energy transfered into the atmosphere) and dust's reflectivity (about +/- 0.3 percent of total energy transfered into the atmosphere) indicate that any correlation between dust and the impact of solar activity would be very weak (around 3 ppm). At 3000 ppm, dust's direct effects via atmospheric dust levels are the more important topic to look at, as confirmed by our further discussions with Professor Kok.

That said the key conclusion of this article -- that warming models need to be re-run with accurate dust info or risk offering misleading conclusions -- still stands, albeit via a different mechanism than we previously thought. We apologize for the confusion concerning the relationship between solar activity and dust levels.

We'd also like to thank Professor Kok for taking the time to discuss some of this study's finer points. We're looking forward to doing an interview with him on the topic of climate modeling in the near future.

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Is that a lot of the self proclaimed "environmentalists" are actually quite ignorant. Mostly dressed in a deliberately non-conformist way, despite actually conforming to the stereotype of their peers. For example, picture an environmentalist, do you see them in a suit? Why not? Because they are mostly prejudiced themselves despite claiming to have the upper hand in the morality meter.

Your average "environmentalist" will be typically vegan, which started a middle class rebellion against what they thought were their middle class parents as part of the establishment. Generally they tend to value animal life above human life. The have political tendencies towards anarchists and alternative groups.

They claim to be learned yet refuse to accept any challenge to their authority (despite them being against authority) or to their viewpoint (despite them rebelling against their conservative parents).

In effect, they are spoilt little Brats, that really couldn't care less about the environment, as it's much more to do with their social standing amongst their peers that is important. They have a hierarchical system in just the same way as the political right do. They have their own agendas, and manipulate facts, figures, data, and spread propaganda to further their own cause.

In effect, they are the opposite side of the same coin they proclaim they are against.

Some may say this is a check and a balance, and to a certain extent I agree. But if the distance between the two sides of the coin becomes so great, that the coin itself shall be torn apart, and the majority in the middle with them.

But above all else, it's their pomposity and self righteousness that really grates on me. They must think we are all idiots to not see through their hypocrisy.

quote: But above all else, it's their pomposity and self righteousness that really grates on me. They must think we are all idiots to not see through their hypocrisy.

It used to grate me too. But I realized that we all do what we want do to and use whatever to justify our actions, right or wrong. Now, if I "debate" with environmentalists or their wannabees, it's just for fun (I like to argue).

Think of it like Christians: few of them go around looking like Jesus with long hair and a scraggly beard to preach peace, love, and happiness. Most of them put on a Sunday suit, keep shaved faces and talk about burning witches or crusades against Muslims.

Some environmentalists are pretty extreme. Others of us are just looking for ways to reduce the negative effects we have on the environment.

Al Gore is NOT an environmentalist. He is a "state-capitalist" - one who believes in his connections and ability to control things to fund his outrageous ego and narcisissim.

His father was one of the worst environmental terrorists the USA has ever seen.

Al Gore has profited over $100 million in his support for the AGW scam. His motivation is pure greed and power...nothing else.

He is a complete hypocrite wasting 23 X's more energy than the average household in the USA...etc...

CFL light bulbs are a perfect example of the "fake green - envrionmentalists" out there. Introduce a product that if it breaks would amount to a hazardous spill. Incredible...but why CFL...oh yeah their cronies could produce them and they all could make money off it? Didn't they get rid of thermostats that had mercury switches...now all of a sudden mercury is all the rage...LOL.

The sheeple of world are complete fools...get the facts...and have your voice heard before they herd you into global enslavement.

You insult me first off. You inject Christians into the argument where it wasn't before. You fail to make the connection. You insult me again. You have the hypocrisy to think that simply attending a church makes you a Christian [because what you actually believe doesn't matter ... or does it?]. The list goes on and on.

quote: The initial poster was basically saying that all environmentalists are dirty hippies.

Wah. Everybody, all together now, POOR BABY! Somebody wrote, actually wrote an insult on the Internet? O no! How derisive! How sarcastic!

And to think the reason for this is that you feel threatened about science eroding the hype surrounding AGW. Go cry on Al Gore's shoulder, not mine. I'm sure he'll share your pain. But not his money. Hah!

quote: You have the hypocrisy to think that simply attending a church makes you a Christian [because what you actually believe doesn't matter ... or does it?].

To be fair most of the "christians" that I know seem to feel the same way. I have several cousins who are born again, go to church every Sunday, pray before every meal that are the most racist people I know. You can't mention the color of any object without it being made into some kind of racist slur by them. Thank goodness I moved to a different state and only have to deal with them occasionally.I also used to have long hair and a beard. A lot of the people that I dealt with didn't approve even though they worshiped a guy with long hair and beard.

When I was a child I had this preconceived notion of what a Christian is. They had to be lily white. Say "yes mam" and "no sir". They had to turn-the-cheek to the point of being a door-mat ... after-all, you have to be fair. They couldn't say "damn" or even "darn". "Shazam" was kind of pushing it. So was "golly". I suppose this all falls under the category of wusification.

I'm disappointed I didn't live up to those rules better. If only somebody would've said something! But now, you look at environmentalists and they've taken on the mantle of spineless-milquetoasts and/or bloated-bigots. Better them than me.

Don't take it too personally. I think he just wanted to cry on my shoulder. How he came to believe I was a Christian I'll never know. Intellectual curiosity is not the same as buying into the mythology.

He still has a hard time linking the fact that Jesus was a hippy with the fact that environmentalists are often categorized as hippies. But that's OK. I know he's suffering from inflammation.

Never said such a thing and never implied such. Perhaps you're delusional, or simply put out that your pet AGW is a theory in crisis.

If I were you, I would have to continue to double-down by deflecting criticism away from Environmentalists -- wasn't that what the thread's about(?). And above all, don't talk about the science. Dust particles can be largely ignored in all current models. Only somebody with intellectual curiosity would look into that.

quote: You insult me first off. You inject Christians into the argument where it wasn't before. You fail to make the connection. You insult me again. You have the hypocrisy to think that simply attending a church makes you a Christian [because what you actually believe doesn't matter ... or does it?]. The list goes on and on.

quote: Wah. Everybody, all together now, POOR BABY! Somebody wrote, actually wrote an insult on the Internet? O no! How derisive! How sarcastic! And to think the reason for this is that you feel threatened about science eroding the hype surrounding AGW.

Wrong! Al Gore is first and foremost a capitalist who sometimes wears the suit of an environmentalist. Be clear on this. Environmentalism is his business . Were it not highly profitable he would likely not be as involved.

It would be more suspect if he espoused solar investment without investing himself. His film pulled in a cool 50 million. It's about the environment. Where do you suppose he ought to invest his time and money?